To simulate volume and density, temperature... You always got to start from scratch. Think about what you want to achieve, then start preparing your ingredient, start up the fire then, always keep tweaking and mix with salt, pepper until it feels right. So...... First you need to have a Source, then DOP , then only output. What source carrying is all the emit geometry, mountain, transform, trail(to create velocity), fluid source(create density volume) and then a Null (as a Final control for this source). An easier and straight forward way to explain is a base foundation. Once you got things set, then it's time to create DOP(Dynamic Operator Network)- to contain the pyroSolver, smokeObjects, fluid, drag controller. My render today is incomplete, not yet using the microSolver to change the shape and fix the dissipation. And! I found Houdini calling playlist as flip book...! Interesting haha! Still catching the world! So excited every time opening Houdini!. Feel like to finish this as soon as possible! But get caught up on assignment..........!